Reactor alloy of syndiotactic polystyrene having high impact resistance

ABSTRACT

The reactor alloy of syndiotactic polystyrene according to the present invention is prepared by polymerizing vinyl aromatic monomer and rubbery elastomer and optionally polyphenylene ether under transition metal catalyst and cocatalyst, which comprises (a) 50-99% by weight of syndiotactic polystyrene, (b) 1-50% by weight of rubbery elastomer, and optionally (c) 0.1-10% by weight of polyphenylene ether. The reactor alloy of the present invention has good dispersibility and high interfacial strength in comparison with a melt blend by polymerizing styrene monomer and rubbery elastomer for impact modifier. And the reactor alloy of the present invention is greatly enhanced in impact resistance in comparison with a melt blend same amount of rubber component as reactor alloy of the present invention without impairing heat resistance and elastic modulus by further comprising polyphenylene ether.

TECHNICAL FIELD

[0001] The present invention relates to a reactor alloy of syndiotacticpolystyrene having high impact resistance. More particularly, thepresent invention relates to a reactor alloy of syndiotactic polystyrenegreatly enhanced in impact resistance in comparison with a melt blendwithout impairing heat resistance and elastic modulus by introducingrubbery elastomer and polyphenylene ether.

BACKGROUND ART

[0002] A styrenic polymer with syndiotactic configuration (hereinafter‘sPS’) is excellent in heat resistance and chemical resistance but ispoor in impact resistance. Therefore, it has heretofore been limited inthe scope of application usable as a construction material. In order tosolve the problem, improvement has been made on the impact resistance ofsPS. For example, Japanese Patent Application Laid-Open Nos. 62-257950(1987), 1-279944 (1989) and 2-64140 (1990) disclose that the impactresistance of sPS can be improved by blending a rubbery elastomer.Especially, Japanese Patent Application Laid-Open No.1-279944 (1989)shows that an atactic polystyrene incorporated in a rubbery elastomer(block or graft copolymer) acts as a compatibilizer, thereby increasingimpact resistance. In addition, Japanese Patent Application Laid-OpenNo.1-279944 (1989) employs a polyphenylene ether as well as a rubberyelastomer, resulting in a great enhancement of impact resistance.

[0003] However, the above-mentioned techniques have some disadvantagesin that a block or graft copolymer or a rubbery component containingatactic polystyrene chain has a low compatibility with sPS, resulting inununiform dispersibility and low interfacial strength of the rubbery.Therefore, the enhancement of impact resistance has still beeninsufficient. Further, in the case of adding a large amount of apoly(phenylene ether) for the purpose of enhancing the impactresistance, addition of a poly(phenylene ether) inevitably brings aboutdeterioration of the resultant composition with respect to hue andlong-term heat resistance as well as decrease in crystallinity of sPS.

[0004] In order to solve the above-mentioned problems, U.S. Pat. No.6,048,932 shows an increase of compatibility between components bychemically treating sPS, a rubbery elastomer, polyphenylene ether etc.with maleic anhydride or amine to induce chemical bonds between thecomponents. However, since interfacial strength between the phases isstill insufficient, there exists limitation in modified impactresistance. Further, addition of a process for the chemical treatmentcauses economical and technical disadvantages.

[0005] Accordingly, the present inventors have developed a syndiotacticpolystyrene which is greatly enhanced in impact resistance without useof any special compatibility agent Further, the styrenic resincomposition of the present invention comprising sPS, thermoplastic resinor rubbery elastomer, and polyphenylene ether can be produced bypalletizing after polymerization without using a complicated extruder,and the sPS composition is greatly enhanced in impact resistance.

OBJECT OF THE INVENTION

[0006] A feature of the present invention is the provision of a reactoralloy of syndiotactic polystyrene having high impact resistance.

[0007] Another feature of the present invention is the provision of asyndiotactic polystyrene having high impact resistance with no use of acompatibilizer.

[0008] A further feature of the present invention is the provision of areactor alloy of syndiotactic polystyrene having good compatibilitybetween the components.

[0009] A further feature of the present invention is the provision of asyndiotactic styrenic resin composition with advantages in controllingreactor fouling and heat of polymerization in the preparation ofsyndiotactic polystyrene resin composition.

[0010] A farther feature of the present invention is the provision of asyndiotactic styrenic resin composition suitable for injection orextrusion molding.

[0011] Other objects and advantages of this invention will be apparentfrom the ensuing disclosure and appended claims.

SUMMARY OF THE INVENTION

[0012] The reactor alloy of syndiotactic polystyrene according to thepresent invention is prepared by polymerizing vinyl aromatic monomer andrubbery elastomer under the catalyst system consisting of a transitionmetal catalyst and a cocatalyst, which comprises (a) 50-99% by weight ofsydiotactic polystyrene; (b) 1-50% by weight of rubbery elastomer, andoptionally (c) 0.1-10% by weight of polyphenylene ether. The reactoralloy of syndiotactic polystyrene according to the present invention hasan enhanced impact resistance in comparison with a melt blend.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a scanning electron microscope (SEM) photograph of aninjection molded test piece of the reactor alloy prepared in accordancewith the method of Example 2; and

[0014]FIG. 2 is a scanning electron microscope (SEM) photograph of aninjection molded test piece of the melt blend prepared in accordancewith the method of Comparative Example 8.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The reactor alloy of syndiotactic polystyrene having high impactresistance according to the present invention can be prepared byreacting vinyl aromatic monomer, rubbery elastomer and optionallypolyphenylene ether under the catalyst system consisting of a transitionmetal catalyst and a cocatalyst. The reactor alloy of syndiotacticpolystyrene of the present invention comprises (a) 50-99% by weight ofsyndiotactic polystyrene having 30-99% (triad) of syndiotacticity; (b)1-50% by weight of rubbery elastomer; and optionally (c) 0.1-10% byweight of polyphenylene ether.

[0016] (a) Syndiotactic Polystyrene

[0017] The styrenic polymer in the reactor alloy of syndiotacticpolystyrene of the present invention has a syndiotactic configurationand is employed as a matrix The syndiotactic configuration in thestyrenic polymer has a stereostructure in which phenyl groups as sidechains are located alternately at opposite directions relative to themain chain consisting of carbon-carbon bonds. Tacticity isquantitatively determined by the nuclear magnetic resonance method(¹³C-NMR method) using a carbon isotope. The tacticity can be shown interms of proportions of structural units continuously connected to eachother, i.e., a diad in which two structural units are connected to eachother, a triad in which three structural units are connected to eachother and a pentad in which five structural units are connected to eachother. The syndiotactic configuration can be characterized by ¹³C-NMRshowing chemical shifts of methine having a phenyl group depending onthe proportion of a racemic structure and a meso structure.

[0018] The syndiotactic polystyrene of the present invention includespolystyrene, poly(alkylstyrene), poly(halogenated styrene),poly(alkoxystyrene), poly(vinyl benzoate), hydrogenated polystyrene, thecopolymers thereof, and the mixtures thereof. It is preferable that thesyndiotactic polystyrene has a proportion of racemic diad of at least75%, more preferably at least 85%, or a proportion of racemic pentad ofat least 30%, more preferably at least 50%.

[0019] The poly(alkylstyrene) includes poly(methylttyrene),poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene),poly(phenylstyrene), poly(vinylnaphthalene) and poly(vinylstyrene) andthe like. The poly(halogenated styrene) includes poly(chlorostyrene),poly(bromostyrene), and poly(fluorostyrene) and the like. Thepoly(alkoxystyrene) includes poly(methoxystyrene), andpoly(ethoxystyrene) and the like.

[0020] More particularly, the above-mentioned styrenic polymers arepolystyrene, poly(p-methylstyrene), poly(m-methylstyrene),poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene),poly(p-fluorostyrene), hydrogenated polystyrene and the copolymersthereof

[0021] The above-mentioned styrenic polymer may be used alone or incombination with one another.

[0022] The weight-average molecular weight of the styrenic polymer to beused in the present invention is not specifically limited, but isdesirably 10,000 or more, more desirably 50,000 or more. If theweight-average molecular weight is less than 10,000, it is unfavorablebecause the thermal or mechanical properties are sometimes deterioratedThe molecular-weight distribution is not specifically limited as well,but may be in a wide range.

[0023] Vinyl Aromatic Monomer

[0024] The styrenic polymer having syndiotactic configuration can beproduced by polymerizing a vinyl aromatic monomer in the presence orabsence of a solvent by the use of a metallocene catalyst and acocatalyst. In addition, the impact-resistant sPS resin compositionemploying poly(halogenated alkylstyrene) and the hydrogenated productthereof can be produced by the processes described in Japanese PatentApplication Laid-Open Nos. 46912(1989) and 178505(1989), respectively.

[0025] The vinyl aromatic monomer of the present invention isrepresented by the formulae (A) and (B):

[0026] In formula (A), J¹ is a hydrogen; a halogen; or a substitutinggroup containing at least one of carbon, oxygen, silicon, phosphorus,sulfur, selenium and tin; and m is an integer of 1 to 3. If m is 2 or 3,J¹s may be different each other.

[0027] In formula (B), J¹ is a hydrogen; a halogen; a substituting groupcontaining at least one of carbon, oxygen, silicon, phosphor, sulfur,selenium and tin; J² is a substituting group of C₂₋₁₀ having at leastone unsated bond; m is an integer of 1 to 3, if m is 2 or 3, J¹s may bedifferent each other, and n is 1 or 2, if n is 2, J²s may be differenteach other.

[0028] The representative examples of formula (A) are alkylstyrene;halogenated styrene; halogen-substituted alkylstyrene; alkoxystyrene;vinylbiphenyl; vinylphenylnaphthalene; vinylphenylanthracene;vinylphenylpyrene; trialkylsilylvinylbiphenyl;trialkylstanylvinylbiphenyl; alkylsilylstyrene; carboxylmethylstyrene;alkylesterstyrene; vinylbenzenesulfonate; andvinylbenzyldialkoxyphosphite and the like.

[0029] The representative examples of alkylstyrene are styrene,methylstyrene, ethylstyrene, butylstyrene, p-methylstyrene,p-tert-butylstyrene, and dimethylstyrene; those of halogenated styreneare chlorostyrene, bromostyrene, and fluorostyrene; those ofhalogen-substituted: alkylstyrene are chloromethylstyrene,bromomethylstyrene, and fluoromethylstyrene; those of alkoxystyrene aremethoxystyrene, ethoxystyrene, and butoxystyrene; those of vinylbiphenylare 4-vinylbiphenyl, 3-vinylbiphenyl, and 2-vinylbiphenyl; those ofvinylphenylnaphthalene are 1-(4-vinylbiphenylnaphthalene),2-(4-vinylbiphenylnaphthalene), 1-(3-vinylbiphenylnaphthalene),2-(3-vinylbiphenylnaphthalene), and 1-(2-vinylbiphenylnaphthalene);those of vinylphenylanthracene are 1-(4-vinylphenyl)anthracene,2-(4-vinylphenyl)anthracene, 9-(4-vinylphenyl)anthracene,1-(3-vinylphenyl)anthracene, 9-(3-vinylphenyl)anthracene, and1-(4-vinylphenyl)anthracene; those of vinylphenylpyrene are1-(4-vinylphenyl)pyrene, 2-(4-vinylphenyl)pyrene,1-(3-vinylphenyl)pyrene, 2-(3-vinylphenyl)pyrene,1-(2-vinylphenyl)pyrene, and 2-(2-vinylphenyl)pyrene; that oftrialkylsilylvinylbiphenyl is 4vinyl-4-trimethylsilylbiphenyl; and thoseof alkylsilylstyrene are p-trimethylsilylstyrene,m-trimethylsilylstyrene, o-trimethylsilylstyrene,p-triethylsilylstyrene, m-triethylsilylstyrene, ando-triethylsilylstyrene.

[0030] The representative examples of formula (1) are divinylbenzenesuch as p-divinylbenzene and m-divinylbenzene; trivinylbenzene; andarylstyrene such as p-arylstyrene and m-arylstyrene.

[0031] Metallocene Catalysts and Cocatalysts

[0032] A conventional catalyst for preparing polystyrene having highsyndiotacticity can be employed in the present invention, but is notlimited particularly. In general, metallocene catalysts consisting of atransition metal compound of Group IV element of the Periodic Table canbe used. Preferably, a titanium compound of Group IV can be used in themetallocene catalyst system. The catalysts are disclosed in U.S. Ser.Nos. 08/844,109 and 08/844,110 in detail.

[0033] In the present invention, the metallocene catalyst system uses acocatalyst. The cocatalyst is an organometallic compound such as alkylaluminoxane and alkyl aluminum compound, which are known to an ordinaryskilled person in the art. The representative examples of allylaluminoxane are methyl aluminoxane (MAO), modified methyl aluminoxane(TAO). The alkyl aluminoxane has a repeating unit of the followingformula (C). The alkyl aluminoxane is divided into a linear alkylaluminoxane represented by the following formula (D) and a cyclic alkylaluminoxane represented by the following formula (E):

[0034] where R¹ is an alkyl group of C₁₋₆ and q is an integer of 0-100.

[0035] A mixture of a non-coordinated Lewis acid and an alkyl aluminumcan be used as a cocatalyst. The non-coordinated Lewis acid is selectedfrom the group consisting of N,N-dimethylanetetrakis(pentafluorophenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, and ferroceriumtetrakis(pentafluorophenyl)borate and tris(pentafluorophenyl)borate. Thealkylaluminum is selected from the group consisting oftrimethylaluminum, triethylaluminum, diethylaluminum chloride,dimethylaluminum chloride, triisobutylaluminum, diisobutylaluminumchloride, tri(n-butyl)aluminum, tri(n-propyl)aluminum,triisopropylaluminum and the like. Among these triisobutylaluminum ispreferably used in particular.

[0036] (b) Rubbery Elastomer

[0037] A rubbery elastomer having an olefinic component of the presentinvention is used for the purpose of improving the impact resistance ofreactor alloy.

[0038] Such rubbery elastomer contains, as a monomer unit in itsstructure, an olefinic component such as ethylene, propylene, butylene,octene, butadiene, isoprene, norbornene, norbornadiene andcyclopentadiene. Specific examples of such rubbery elastomer includenatural rubber; polybutadiene; polyisoprene; polyisobutylene; neoprene;ethylene/styrene pseudo random copolymer (ESI); styrene/butadiene blockcopolymer (SBR); styrene/butadieneistyrene block copolymer (SBS);hydrogenated styrene/butadiene/styrene block copolymer)(SEBS);styrene/isoprene block/styrene block copolymer (SIS); hydrogenatedstyrene/isoprene block/styrene block copolymer (SEPS);ethylene/propylene rubber (EPM); ethylene/propylene/dien rubber (EPDM);and rubber formed by modifying any of the foregoing with a modifyingagent Preferable rubbery elastomers among these are SEBS, SBR, SBS, EPMand EPDM.

[0039] Specific examples of the polyolefin include isotacticpolypropylene, syndiotactic polypropylene, atactic polypropylene, blockpolypropylene, random polypropylene, high-density polyethylene,low-density polyethylene, linear low-density polyethylene,ethylene/octane copolymer, cyclic polyolefin, polybutene,1,2-polybutadiene and a copolymer thereof.

[0040] The rubbery elastomer is blended in an amount of 1 to 50%,preferably 2 to 40%, more preferably 5 to 40% by weight. A blendingamount less than 1% by weight results in little effect on theimprovement of impact resistance, whereas more than 50% by weightunfavorably brings about remarkable deterioration of modulus ofelasticity as well as heat resistance of the resin compositionEspecially, the rubbery elastomer (b) includes a styrene/olefin block orgraft copolymer having at least 180° C. of a micro-phase separationtemperature, which plays a role as a compatibilizing agent between sPSand polyolefin. The temperature higher than micro-phase separationtemperature results in a failure for forming a micro-phase separationstructure, whereas the temperature lower than that leads to formation ofsuch structure.

[0041] The micro-phase separation temperature of the rubbery elastomeris determined by diluting with dioctyl phthalate a solution with aconcentration of 60% by weight. The above-exemplified olefiniccomposition or rubbery elastomer of polyolefin may be used alone or incombination with at least one component

[0042] (c) Polyphenylene Ether

[0043] The reactor alloy of syndiotactic polystyrene having high impactresistance according to the present invention may optionally comprisepolyphenylene ether. The poly(phenylene ether) is prepared usually byoxidative coupling reaction of di- or tri-substituted phenol in thepresence of a cupramine complex, as shown in U.S. Pat. Nos. 3306874,3306875, 3257357 and 3257358. The cupramine complex there may be derivedfrom any one of primary, secondary and tertiary amines.

[0044] Specific examples of the suitable poly(phenylene ether) include

[0045] poly(2,3-diethylethyl-1,4-phenylene ether),

[0046] poly(2-methylchloromethyl-1,4-phenylene ether),

[0047] poly(2-methylhydroxyethyl-1,4-phenylene ether),

[0048] poly(2-methyl-6-n-butyl-1,4-phenylene ether),

[0049] poly(2-ethyl-6-n-propyl-1,4-phenylene ether),

[0050] poly(2,3,6-trimethyl-1,4-phenylene ether),

[0051] poly[2-(4′-methylphenyl)-1,4-phenylene ether],

[0052] poly(2-bromo-6-phenyl-1,4-phenylene ether),

[0053] poly(2-methyl-6-phenyl-1,4-phenylene ether),

[0054] poly(2-phenyl-1,4-phenylene ether), poly(2-chloro-1,4-phenyleneether), poly(2-methyl-1,4-phenylene ether),poly(2-chloro-6-ethyl-1,4-phenylene ether),poly(2-chloro6-bromo-1,4-phenylene ether),poly(2,6-di-n-propyl-1,4-phenylene ether),poly(2-methyl-6-isopropyl-1,4-phenylene ether),poly(2-chloro-6-methyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dibromo-1,4phenylene ether), poly(2,6-dichloro-1,4-phenyleneether), poly(2,6diethyl-1,4phenylene ether) andpoly(2,6-dimethyl-1,4-phenylene ether), a copolymer thereof, or acopolymer with styrenic compound and the like.

[0055] In addition, a graft copolymer or a block copolymer of anaromatic vinyl compound such as Styrene and the aforestatedpoly(phenylene ether) can be employed. Among the above-mentionedpoly(phenylene ether), poly(2,6-dimethyl-1,4-phenylene ether) isparticularly desirable for use. The above-mentioned poly(phenyleneether) may be used alone or in combination with at least one other.

[0056] The molecular weight of the poly(phenylene ether) is notparticularly limited, but is preferably not less than 0.4dL(deciliter)/g, more preferably not less than 0.5 dL/g of intrinsicviscosity. If the intrinsic viscosity is less than 0.4 dL/g, it isunfavorably less effective in improving the impact resistance of thecomposition. The intrinsic viscosity was measured in chloroform at 25°C.

[0057] The amount of the poly(phenylene ether) to be added is about 0.1to 10%, preferably about 0.5 to 5.0% by weight If the amount of thepoly(phenylene ether) is less than 0.1% by weight, it is less effectivein improving the impact resistance, whereas more than 10.0% by weightunfavorably brings about the deterioration of the moldability of theresin composition as well as the activity of the catalyst.

[0058] (d) Other Additives

[0059] Other additives, such as inorganic filler, may be added to thereactor alloy of the present invention during palletizing process inorder to increase rigidity.

[0060] A nucleating agent may be added in order to acceleratecrystallization of sPS. Any conventional nucleating agents may be usede.g., metal carboxylates such as aluminum di-(pt-butylbenzoate); sodiummethylenebis(2,4-di-t-butylphenol)phosphate; talc; and phthalocyaninederivatives and the like. The nucleating agents may be used alone or incombination thereof.

[0061] Flame retardant and flame retardant aid can be used, such asbrominated polystyrene, brominated syndiotactic polystyrene, brominatedpoly(phenylene ether), etc. as flame retardant, and antimony compoundssuch as antimony trioxide, etc. as flame retardant aid. Any of them maybe used alone or in combination with at least one other.

[0062] Further, (2,6-di-tert-butyl-4-methylphenyl)pentaerythritoldiphosphate (produced by Adeka Argus Co., Ltd. under the trademark“PEP-36”) andtetrakistmethylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)]propionate(produced by Adeka Argus Co., Ltd. under the trademark “MARK A060”) maybe used as an antioxidant. The antioxidant may be used alone or incombination with at least one other.

[0063] Other additives may be added to the reactor alloy of the presentinvention by compounding and blending, when desired.

[0064] The present invention will be described in more detail by thefollowing Examples. The Examples are given only to illustrate thepresent invention and not intended in any way to limit the scope of theinvention.

EXAMPLES

[0065] (a) syndiotactic polystyrene, (b) rubbery elastomer and (c)polyphenylene ether used in the Examples and Comparative Examples are asfollows:

[0066] (a) Preparation of Syndiotactic Polystyrene

[0067] Syndiotactic polystyrene was prepared in a glass reactor equippedwith a temperature controller, a magnetic agitator or a mechanicalagitator, and valves through which the monomers and nitrogen were fed.To the glass reactor substituted with nitrogen gas, 200 ml of purifiedstyrene monomer, triisobutylaluminum (8.0×10⁻³ mol) and methylaluminoxane (concentration of aluminum: 2.0×10⁻³ mol) as a cocatalystwere added with stirring. To the above mixed solution, a certain amountof a catalyst (concentration of titanium=2.0×10⁻⁵ mol) was added tostart polymerization. After reaction for a while, a small amount ofmethanol was added to stop proceeding polymerization The resultingsolution was washed with methanol in excess and sodium hydroxide andthen filtered. The resulting polymer was dried at 90° C. in vacuum forabout 4 hours to obtain 138 g of syndiotic polystyrene.

[0068] The physical properties of the syndiotactic polystyrene obtainedtherefrom are as follows;

[0069] syndiotacticity: 98%

[0070] weight-average molecular weight how): 516,000 and molecularweight distribution (Mw/n): 2.39

[0071] melting point: 273° C.

[0072] (b) Rubbery Elastomer

[0073] (1) Hydrogenated Styrene/Butadiene/Styrene Block Copolymer(SEBS):

[0074] A commercial product (Kraton G-1651) of Shell Co. (vacuum-driedat the temperature of more than 70° C.) was used as SEBS.

[0075] (2) Styrene/Butadiene/Styrene Block Copolymer (SBS):

[0076] A commercial product (411) of LG Chemical Co. of Korea(vacuum-dried at the temperature of more than 70° C.) was used as SBS.

[0077] (3) Ethylene/Styrene pseudo-random copolymer-1 (ESI-1):

[0078] Ethylene/Styrene pseudo-random copolymer-1 was prepared by thesame method shown in European Patent 416,815 A2, having the followingphysical properties:

[0079] styrene contents: 10.8 mol %

[0080] weight-average molecular weight (Mw): 222,000 and molecularweight distribution (Mw/Mn) :1.92

[0081] melting point: 69° C.

[0082] (4) Ethylene/Styrene pseudo-random copolymer-2 (ESI-2):

[0083] Ethylene/Styrene pseudo-random copolymer-2 was prepared by thesame method shown in European Patent 416,815 A2, having the followingphysical properties:

[0084] styrene contents: 25.6 mol %

[0085] weight-average molecular weight (Mw): 79,000 and molecular weightdistribution Mw/r) : 1.84

[0086] (5) Ethylene-Propylene/Dien Terpolymer (EPDM)

[0087] A commercial product (EP57P) of Japan Synthetic Rubber Co.(vacuum-dried at the temperature of more than 70° C.) was used as EPDM.

[0088] (c) Polyphenylene Ether (PPE)

[0089] A commercial product (P401) of Asahi Co. of Japan (vacuum-driedat the temperature of more than 70° C.) was used as PPE.

Examples 1-15

[0090] Reactor Alloy

[0091] Reactor alloys were prepared in the same manner as in the abovepreparation of syndiotactic polystyrene except that purified rubberyelastomer (b) alone or in combination with purified polyphenylene ether(c) was mixed with 200 ml of syndiotactic polystyrene, followed bymelting and then polymerizing. The polymerization conditions and resultsfor Examples 1-15 are shown in Table 1 below. TABLE 1 rubberypolyphenylene polym. yield conversion Example elastomer(b)(g)ether(c)(g) time(min) (%) (%) activity* 1 SEBS 20 4 60 85 33.6 3,050 220 2 60 91 38.0 3,450 3 20 1 30 85 35.2 6,400 4 15 2 60 95 42.9 3,900 510 1 30 93 45.1 8,200 6 5 1 30 85 43.5 7,900 7 SEBS 20 — 30 102 44.68,100 8 10 — 30 125 63.0 11,450 9 ESI-1 16 — 30 100 46.2 8,400 10 7 — 30111 57.2 10,400 11 ESI-2 10 2 60 98 47.3 4,300 12 ESI-2 16 — 30 138 67.012,200 13 10 — 30 123 61.8 11,250 14 SBS 20 4 60 89 38.0 3,250 15 EFDM21 2 60 102 43.5 3,950

[0092] Examples 7-10 and 12-13 which rubbery elastomer (b) alone wasadded to syndiotactic polystyrene without polyphenylene ether showhigher polymerization activities than Examples 1-6 which employspolyphenylene ether. It is thought that rubbery elastomers are dissolvedby styrene monomer, resulting in increase of viscosity, thereby formingminute bubbles in the solution, which plays a role of inhibitingagglomeration of the polymers to increase the activity.

[0093] In addition, if the conversion rate is about 30% or more, thepolymer is in the form of sphere and the powder having 0.51 of bulkdensity with good morphology can be obtained. Accordingly, the polymerstherefrom have good flowability to be an advantage in the process.

[0094] On the other hand, Examples 1-6, 11 and 14-15 which rubberyelastomer (b) and polyphenylene ether (c) were added to syndiotacticpolystyrene show a decrease in activity in accordance with the amount ofpolyphenylene ether, as shown in Table 1, which results from thedecrease in activity of the styrene, since the unshared electron pairsof oxygen atom consisting the ether bond in the polyphenylene ether arecoordinated in the active site of the catalyst.

Comparative Examples 1-8

[0095] Melt Blends

[0096] Comparative Examples 1-8 were conducted with the same amount ofrubbery elastomer (b) and polyphenylene ether (c) in order to comparewith reactor alloy of the Examples. The melt blends were prepared bymelt-kneading sPS homopolymer with rubbery elastomer (b) andpolyphenylene ether (c) using Haake Mixer for 3 minutes at 280° C. Theresults are shown in Table 2. TABLE 2 physical properties components (wt%) Izod Rubbery polyphenylene flexural impact sPS(a) elastomer(b)ether(c) strength strength Examples 1 75.7 SEBS 22.1 2.2 18,550 40.3 271.8 23.5 4.7 18,980 39.8 3 75.3 23.5 1.2 19,220 34.9 4 82.1 15.8 2.122,450 20.5 5 88.1 10.8 1.1 28,500 13.4 6 92.9 5.9 1.2 29,410 7.4 7 80.4SEBS 19.6 — 19,280 8.6 8 92.0 8.0 — 28,020 3.6 9 84.0 ESI-1 16.0 —21,160 1.7 10 93.7 6.3 — 28,450 1.3 11 88.4 ESI-2 11.6 — 28,090 1.4 1291.9 8.1 — 29,090 1,5 13 87.8 ESI-2 10.2 2.0 28,400 4.6 14 73.0 SBS 22.54.5 16,580 23.9 15 77.1 EPDM 20.5 2.0 28,720 3.4 Comparative 1 72.0 23.54.5 24,500 10.3 Examples 2 75.7 SEBS 22.1 2.2 25,430 9.3 3 88.1 10.8 1.126,700 3.2 4 80.4 SEES 19.6 — 22,810 5.6 5 93.7 ESI-1 6.3 — 25,440 1.0 687.8 ESI-2 10.2 2.0 28,020 3.0 7 77.1 EPDM 20.5 2.0 29,510 1.9 8 74.0SEBS 18.0 4.0 17,950 29.8 SEBS-MA* 4.0

[0097] As shown in Table 2, the reactor alloys of Examples show highimpact strength compared to melt blends of the Comparative Examples.Comparing Examples 1, 2 and 5 with Comparative Examples 2, 1 and 3respectively, the reactor alloy products have higher impact resistancethan melt blend products. Additionally, as is demonstrated in Example 7and Comparative Example 4 which do not contain polyphenylene ether, thesame results can be obtained. Further, if SEBS used as rubbery elastomer(b) is substituted with ESI, EPDM, SBS and the like, the same resultscan be obtained.

[0098] Furthermore, the reactor alloy of Example 2 shows an impactstrength four times as high as the melt blend of Comparative Example 1having the same amount of rubbery elastomer as in Example 2 and shows agood flexural modulus which results from its good mixing property.

[0099] U.S. Pat. No. 6,048,932 employs SEBS-MA prepared by grafting SEBSand maleic anhydride in order to enhance the mixing property of sPS andSEBS as a compatibilizing agent As shown in Comparative Example 8, thecomposition was endowed with enhanced impact resistance compared tothose not containing SEBS. However, the impact resistance of that ofU.S. Pat. No. 6,048,932 shows a low value compared to that of thepresent invention.

[0100] In addition, since U.S. Pat. No. 6,048,932 needs a process ofgrafting SEBS and maleic anhydride, it brings about commercialdisadvantage. As it is clear from the results, the reactor alloy ofsyndiotactic polystyrene of the present invention is enhanced in impactresistance as well as flexural modulus compared to any otherconventional melt blend compositions.

[0101] The microstructure of the reactor alloy of the present inventionwas measured by scanning electron microscope (SEM) photograph. Therepresentative results are shown in FIGS. 1 and 2 for Example 2 andComparative Example 8, respectively. The injection molded test pieces ofthe reactor alloy (Example 2) and the melt blend(Comparative Example 8)are cut in liquid nitrogen, followed by liquating the rubber-phasecomponent in toluene for 30 minutes at 50° C. As shown in FIGS. 1 and 2,the rubber phase domain of the reactor alloy (Example 2) according tothe present invention has a fine and uniform surface in comparison withthat of the melt blend (Comparative Example 8) comprising acompatibilizing agent (SEBS-MA).

[0102] Further, when polymers from the Examples and Comparative Exampleswere eluted by hot toluene for more than 24 hours, the amount of rubberyelastomer (b) and polyphenylene ether extracted from the polymer of thepresent invention was less than that of the melt blend at the samecondition. By this result, it was thought that part of remaining doublebonds of rubbery elastomer (b) is copolymerized with sPS in thepolymerization, thereby causing the reactor alloy of the presentinvention to have good mechanical properties in comparison with the meltblend of the same composition.

[0103] As shown in Tables 1 and 2, use of polyphenylene ether makes thepolymerization activity decreased, while, it makes the Izod impactstrength increased. Therefore it is preferable to add the polyphenyleneether to prepare a reactor alloy of syndiotactic polystyrene having highimpact resistance.

[0104] The present invention can be easily carried out by an ordinaryskilled person in the art. Many modifications and changes may be deemedto be with the scope of the present invention as defined in thefollowing claims.

What is claimed is:
 1. A reactor alloy of syndiotactic polystyreneprepared by polymerizing vinyl aromatoic monomer and rubbery elastomerunder the catalyst system consisting of a transition metal catalyst anda cocatalyst, which comprises (a) 50-99% by weight of syndiotacticpolystyrene and (b) 1-50% by weight of rubbery elastomer.
 2. The reactoralloy of syndiotactic polystyrene as defined in claim 1, wherein saidvinyl aromatic monomer is represented by following formulae (A) and (B):

where in formula (A), J¹ is a hydrogen; a halogen; or a substitutinggroup containing at least one of carbon, oxygen, silicon, phosphorus,sulfur, selenium and is tin; and m is an integer of 1 to 3, and if m is2 or 3, J¹s may be different each other, and where in formula (B), J¹ isa hydrogen; a halogen; a substituting group containing at least one ofcarbon, oxygen, silicon, phosphor, sulfur, selenium and tin; J² is asubstituting group of C₂₋₁₀ having at least one unsaturated bond; m isan integer of 1 to 3, and if m is 2 or 3, J¹s may be different eachother; and n is 1 or 2 and if n is 2, J²s may be different each other.3. The reactor alloy of syndiotactic polystyrene as defined in claim 2,wherein said vinyl aromatic monomer represented by formula (A) isselected from the group consisting of alkylstyrene such as styrene,methylstyrene, ethylstyrene, butylstyrene, p-methylstyrene,p-tert-butylstyrene, and dimethylstyrene; halogenated styrene such aschlorostyrene, bromostyrene, and fluorostyrene; halogen-substitutedalkylstyrene such as chloromethylstyrene, bromomethylstyrene, andfluoromethylstyrene; alkoxystyrene such as methoxystyrene,ethoxystyrene, and butoxystyrene; vinylbiphenyl such as 4-vinylbiphenyl,3-vinylbiphenyl, and 2-vinylbiphenyl; vinylphenylnaphthalene such as1-(4-vinylbiphenylnaphthalene), 2-(4-vinylbiphenylnaphthalene),1-(3-vinylbiphenylnaphthalene), 2-(3-vinylbiphenylnaphthalene), and1-(2-vinylbiphenylnaphthalene); vinylphenylantbracene such as1-(4-vinylphenyl)anthracene, 2-(4-vinylphenyl)anthracene,9-(4-vinylphenyl)anthracene, 1-(3-vinylphenyl)anthracene,9-(3-vinylphenyl)anthracene, and 1-(4-vinylphenyl)anthracene;vinylphenylpyrene such as 1-(4-vinylphenyl)pyrene,2-(4-vinylphenyl)pyrene, 1-(3-vinylphenyl)pyrene,2-(3-vinylphenyl)pyrene, 1-(2-vinylphenyl)pyrene, and2-(2-vinylphenyl)pyrene; trialkylsilylvinylbiphenyl such as4-vinyl4-triethylsilylbiphenyl; alkylsilylstyrene such asp-trimethylsilyktyrene, m-trimethylsilylstyrene,o-trimethylsilylstyrene, p-triethylsilylstyrene, m-triethylsilylstyrene,and o-tiethylsilylstyrene; carboxylmethylstyrene; alkylesterstyrene;vinylbenzenesulfonate; and vinylbenyldialkoxyphosphite; and the vinylaromatic monomer represented by formula (B) is selected from the groupconsisting of divinylbenzene such as p-divinylbenzene andm-diviylbenzene, trivinylbenzene, and arylstyrene such as p-arylstyreneand m-arylstyrene.
 4. The reactor alloy of syndiotactic polystyrene asdefined in claim 1, wherein said syndiotactic polystyrene is selectedfrom the group consisting of polystyrene, poly(alkylstyrene),poly(halogenated styrene), poly(alkoxystyrene), poly(vinyl benzoate),hydrogenated polystyrene, the copolymers thereof, and the mixturesthereof.
 5. The reactor alloy of syndiotactic polystyrene as defined inclaim 1, wherein said syndiotactic polystyrene has the syndiotacticstructure having a proportion of racemic diad of at least 75%, or aproportion of racernic pentad of at least 30%.
 6. The reactor alloy ofsyndiotactic polystyrene as defined in claim 1, wherein the weightaverage molecular weight of said syndiotactic polystyrene is about10,000 or more.
 7. The reactor alloy of syndiotactic polystyrene asdefined in claim 1, wherein said rubbery elastomer (b) is selected fromthe group consisting of natural rubber; polybutadiene; polyisoprene;polyisobutyrene; neoprene; ethyleneistyrene psuedo random copolymer(ESI); styrene/butadiene block copolymer (SBR);styrenetbutadiene/styrene block copolymer (SBS); hydrogenatedstyrenelbutadienelstyrene block copolymer (SEBS); styrene/isopreneblock/styrene block copolymer (SIS); hydrogenated styrene/isopreneblock/styrene block copolymer (SEPS); ethylene/propylene rubber (EPM);ethylene/propylene/dien rubber (PDM); and rubber formed by modifying anyof the foregoing with a modifying agent
 8. The reactor alloy ofsyndiotactic polystyrene as defined in claim 1, wherein said transitionmetal catalyst is a metallocene catalyst comprising a transition metalcompound of Group IV element of the Periodic Table.
 9. The reactor alloyof syndiotactic polystyrene as defined in claim 1, wherein saidcocatalyst is alkyl aluminoxane or alkyl aluminum compound, wherein saidalkyl aluminoxane is a compound such as methyl aluminoxane (MAO),modified methyl aluminoxane (MMAO) having the unit represented by thefollowing formula (C) comprising a linear alkyl aluminoxane representedby the following formula (D) and a cyclic alkyl aluminoxane representedby the following formula (E):

where R¹ is an alkyl group of C₁₋₆ and q is an integer of 0-100.
 10. Thereactor alloy of syndiotactic polystyrene as defined in claim 1, whereinsaid cocatalyst is a mixture of a non-coordinated Lewis acid and analkyl aluminum, wherein said non-coordinated Lewis acid is selected fromthe group consisting of N,N-dimethylanilinetetrakis(pentafluorophenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, and ferroceriumtetarkis(pentafluorophenyl)borate and tris(pentafluorophenyl)borate, andwherein said alkylaluminum is selected from the group consisting oftrimethylaluminum, triethylaluminum, diethylaluminum chloride,dimethylaluminum chloride, triisobutylaluminum, diisobutylaluminunchloride, tri(n-butyl)aluminum, tri(n-propyl)aluminum, andtriisopropylaluminum.
 11. The reactor alloy of syndiotactic polystyreneas defined in claim 1, further comprising an inorganic filler, anucleating agent, a flame retardant, a light stabilizer, and/or anantioxidant.
 12. The reactor alloy of syndiotactic polystyrene asdefined in any one claim of claims 1-11, further comprising 0.1-10% byweight of (c) polyphenylene ether.
 13. The reactor alloy of syndiotacticpolystyrene as defined in claim 12, wherein said polyphenylene ether(c)is selected from the group consisting ofpoly(2,3-dimethyl-6-ethyl-1,4-phenylene ether),poly(2-methyl-6-chloromethyl-1,4-phenylene ether),poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether),poly(2-methyl-6-n-buty-1,4-phenylene ether),poly(2-ethyl-6-n-propyl-1,4-phenylene ether),poly(2,3,6-trimethyl-1,4-phenylene ether),poly[2-(4′-methylphenyl)-1,4-phenylene ether],poly(2-bromo-6-phenyl-1,4-phenylene ether),poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2-phenyl-1,4-phenyleneether), poly(2-chloro-1,4-phenylene ether), poly(2-methyl- 1,4-phenyleneether), poly(2-chloethyl-1,4-phenylene ether),poly(2-chlorobromo1,4-phenylene ether), poly(2,6-di-n-propy-1,4-phenylene ether), poly(2-methyl-6-isopropyl-1,4-phenylene ether),poly(2-chloro-6-methyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dibromo-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenyleneether), poly(2,6-diethyl-1,4-phenylene ether) andpoly(2,6-dimethyl-1,4-phenylene ether), a copolymer thereof, or acopolymer with styrenic compound and a mixture thereof.